Many devices have been developed for use during exercise to track various parameters of a user's workout. For example, GPS watches can track the total distance traveled by the user, pedometers can count a number of steps a user takes, heart rate monitors can track a user's heart rate, etc.
Although such devices provide beneficial information about the workout, they are unable to distinguish between different types of exercise. For example, a GPS watch, because it only tracks changes in the user's GPS coordinates, cannot determine whether the user is walking, running, biking, or driving in a car. Similarly, a pedometer can detect the occurrence of a step using an accelerometer due to the sudden change in acceleration when the user's foot hits the ground, but cannot determine the specific motion the user's foot is making before hitting the ground.